It may happen due to broken network connection, a server issue and/or a conflict from other plugins and themes.
I'll advise to:
IMPORTANT: Take full backup of your website and database beforehand. It is highly advised to try the following on a staging/dev site first, so your live website isn't compromised.
- deactivate all plugins except WPML.
- switch to a standard WordPress theme like 2021 or 2023.
- then try updating WPML plugins first.
If this doesn't help, then please unregister WPML, delete the existing key from your wpml.org account, create a new one and register WPML. Then retry.
If none of this works, then try to update plugins manually from Plugins page:
1) Deactivate existing WPML plugins
2) Delete WPML plugins
3) Download latest versions from https://wpml.org/account/downloads/
4) Upload using Plugins -> Add New -> Upload
5) Activate
Please let me know and I'll try my best to further help you on the matter.